I need to update my operating system from 10.5.8 to 10.6, I believe its the one before snow leopard and is just called leopard.

Question

i need to update my operating system from 10.5.8 to 10.6 on my mac mini, I believe its the one before snow leopard and is just called leopard.

Answer 1

You seem to have your OS's confused.   Your profile says 10.6 but you are asking to update from 10.5.8.
10.5.8 is Leopard.   It is also the highest level of Leopard you can achieve.
10.6.(x) is Snow Leopard.   And 10.6.8 is the highest level you can achieve.
If you have 10.6 then all you will need to do is download and apply the combo updater.
If you have 10.5.8, then you will need to review the machine ... Mac OS X v10.6 Snow Leopard -Read the Technical Specifications
Subject the machine will take it, you will then need to buy Snow Leopard from your National on-line Apple store.
Before you start upgrading, back up your files.   If you are unsure how best to do this, the following link is hugely informative.   Most commonly used backup methods: Apple Support Communities
Once you have upgraded to Snow Leopard, your upgrade will take you to 10.6.3 and you then will need to apply the Combo updater.  Mac OS X 10.6.8 Update Combo v1.1
and follow with software updates to pick up the most recent security and iTunes updates.
This will give you the best and highest level includine the App Store.
Good luck.